Treatment of zein solutions



' Patented July 2, 1940 .PA'IITENTJ OFFICE TREATMENT OF ZEIN SOLUTIONS Lloyd Clayton Swallen, Pekin, Ill.,assignor, by mesne assignments, to Corn Products Refining Company, New York, N. Y., a corporation of New Jersey Application August 2,

1937, Serial No. 156,991

I Renewed April 20, 1939 9 Claims. (01. 260- 423) This invention relates to the preparation of zein; and a primary object of the invention is to provide anew and improved process for removing oil and coloring matter from a zein solu- 5 tion wit out leaving any appreciable quantity of the hydrocarbon oil solvent in the solution.

If the zein solventcontains water, as will be the case if the zein is produced by extraction with an aqueous alcohol solution, a further object of the invention is to provide for removing some of the water from the mixture treated so as to reduce the water content of the solvent in the purified solution resulting from the treatment contemplated by this invention. A solution treated so that the maize-oil and coloring matter is completely removed without leaving any ofthe hydrocarbon oil solvent in the solution is desirable for several reasons: If the zein is to be precipitated from the solution with Y water and dried, any hydrocarbon present in the solution will be precipitated with the zein and will not be readily separated from it either before or after drying. Consequently, unless the hydrocarbon is completely removed, contamination of the zein results together with loss of the oil solvent. Furthermore, for many uses it is desirable to have the zein in the form of an alcohol solution. A material saving will be effected if the solution can' be prepared free from the oil solvent and in a relatively stable condition instead of by precipitating, dryingyand re-dissolving the material. Water content is one of the factors controlling stability; and the subordinate object of the invention referred to' above provides a convenient and inexpensive expedient for regulating the water content, or in other words alcohol concentration, of the finished solution.

A zein solution of the type contemplated by this invention may be produced in accordance with the' process disclosed in co-pending application of Lloyd G. Swallen, Serial No. 20.401,'fi1ed May 8, 1935, now Patent No. 2,105,760. Ac-

cording to this process the zein is extracted from gluten meal with an aqueous ethyl alcohol solu- 5 tion of 92% strength, which may be varied within the range of approximately 88 95%, for,

two hours, more or less, at a temperature of 60"v C., practical temperatures ranging from 55 to 65 C. (l31-149 F.) more or less. The alcohol percentage is by volume whenever referred to herein.

The extract may be clarified in any suitable manner, for example, in accordance with the process disclosed in copending application of Lloyd C. Swallen, filed July 26, 1937, Serial No.

155,691. The clarification step is not, however, an essential part of the present invention.

According to copending application of Lloyd C. Swallen, Serial No. 20,402, filed May 8, 1935', now Patent No. 2,133,591,'a hydrocarbon solvent 5 of maize-oil and coloring matter is mixed with the extract, the. mixture allowed to stand until it separates into two liquid layers, the'quantity of the oil solvent being sufiicient to cause this separation into two liquid phases, which may be 10 effected by gravity or centrifugal force'. The lower, heavier layer contains zein; alcohol, some 1 oil solvent (toluol being the preferred oil solvent of application Serial No. 20,402) and somewater.

The light, supernatant layer in the case of a Iii gravity separation contains most of the toluol,

alcohol, oil, coloring matter and a small amount of water. The light supernatant-liquid is removed, and if desired, the heavy liquid is given anotherextraction with oil solvent of the same 20 character; and this operation may be repeated as often as necessary. However, according to this process the final *solution will contain some of the oil solvent; and

this is undesirable for the reasons above stated. 25

According to the present invention the-mixture of zein solution and oil solvent, preferably after one or more gravity separations of the type above described, is first diluted with additional alcohol, in order to give it stabilityunder the 30 subsequent processing steps, although this is not always necessary, and is then subjected to a distilling operation which removes from the liquid treated substantially all of the oil solvent and some water. The oil solvent should be miscible, 35 or at least partially miscible with the zein solvent-and the term miscible is intended to cover partial miscibility--and should not, 'of course, be a solvent; of zein. Preferably vapors of alcohol are introduced into the liquid under 40 distillation so as to displace, by their condensation, the oil solvent in the mixture. Preferably, benzol is used as an oil solvent'in place of toluol because of the lower boiling point of benzol. cause of its higher boiling point the process is relatively inefficient, and requires a larger equipment and the use of more alcohol.

If it is desired to reduce the water content in the purified solution, that is to produce a solu- 56 tion having a relatively high alcohol concentration, which is advantageous in order that the solution be as stable as possible against denatur- ,ization, (i. e. the insolubilizing of the soluble gluten) an increased amount of water may be M It is possible to use toluol but be- 45 extracting gluten meal 2 driven off from the mixture treated during the distilling operation, by adding benzol and alcohol to the solution before distilling; or by gradually introducing into the liquid undergoing distillation additional amounts or benzol at such a rate that the solution remains homogeneous.

The distillation maybe carried out in any suitable form of apparatus by elthera batch process or a continuous process. In order to minimize the detrimental effect of high temperature on the zein, it is preferable to operate at vacuum corresponding to temperatures 01 40 C. to 47 C. (104-117 E). Lower temperatures than these could be used but'would necessitate refrigeration apparatus on the condenser. v

The solvents leaving the zein solutions as vapors can be fractionated in any desired manner and the distillates re-used in the process so thatnone of either of the solvents needs to be lost. The drawing hereto appended is a diagrammatic showing of a form of continuous distilling apparatus suitable for carrying out the process.

The following are specific examples of the application of the invention to practice. These examples are merely informative and illustrative of the process. They are not to be considered as limiting the invention to the particular operating data given.

Example 1 A zein solution containing 6 grams of zein per 100 cubic centimeters of solvent is prepared by with 92% aqueous alcohol in the manner described above. The solution is clarified by settling and filtering; or by'the more elaborate methods disclosed in the aforesaid copending application Serial No. 155,691. To 200 gallons of this solution is added 260 gallons of benzol and the mixture is agitated for five minutes and allowed to settle for an hour. The lighter supernatant liquid layer containing 0.06 gram of protein per 100 cubic centimeters of liquid is drawn of! leaving 42 gallons of heavy zein solution containing 28 grams of zein per 100 cubic centimeters of liquid and having a solvent mixture consisting of 33% benzol, 52% alcohol and 15% of water by weight. The heavy zein solution is diluted with 12 gallons of 92% alcohol. The diluted solution is then run into an evacuated kettle maintained at a vacuum of 24 inches to 26 inches of mercury, and the vapors of 92% alcohol are introduced into the liquid 'in'the kettle until the benzol has been completely displaced. The resulting solution contains 23 grams of protein per 100 centimeters of solvent. The solvent consists of 88% alcohol. No benzol is detectable.

Example 2 If it is desired to increase the alcohol concentration of the final solution the procedure 0! Example 1 is modified by adding to the heavy zein. solution a mixture of ten gallons oil benzol and five gallons of alcohol in place 01' the twelve gallons of alcohol used in said example.

Example 3 Referring to the drawing, l0 designates a still column provided with five perforated plates II, from each of which leads. a pipe l2 to a seal cup I3 on the plate below, except that the lower seal cup is on the bottom of the still. 14 designates a supply tank forthe zein-solution which is connected to the top of the still column by pipe I! having a feed control valve It. The vapor pipe I! leads from the top of thestill to a surface condenser 18, the discharge pipe l9 from which extends into a casing 20 connected by pipe 2i with the vacuum apparatus. The still column has a barometric leg 22 and the condenser a barometric leg 23. 24 is a pipe leading into the bottom section of the still column from the alcohol still (not shown).

The zein solution, diluted as in Example 1, is introduced into the top of the still column at the rate of one gallon per minute. Alcohol vapors corresponding to 92% alcohol, are introduced in the bottomsection of the column, through pipe 24, at such a rate (controlled by valve 25) that the distillate will contain approximately 55% benzol by volume. The column is held under such a vacuum that the temperature at the bottom-of the column is 41 to 42 C. and the temperature at the top 32 to 34 C. (90 to 93 F.). The vapors from the still column are run to the condenser 18, from which the condensate is removed through the baronietric leg 23. The zein solution from the bottom of' the still column passes through the barometric leg 22. It is substantially benzol free and the solvent has an alcohol concentration of 88%.

Example 4 If it is desired to decrease the water content of the benzol free solution, this may be done in the process of Example 3 by introducing benzol little by little into the still column while the distillation is in progress and at such a rate that the solution remains at all times homogeneous.

It is the intention t'ocover allequivalents of the procedures specified and all modifications thereof within the scope of the appended claims.

I claim:

1. Process of treating an aqueous alcohol solution of zein which comprises: mixing benzol with the solution in quantity suflicient to bring about a separation of the mixture into a heavy liquid containing zein, alcohol, water and some benzol, and a lighter liquid containing oil, coloring matter, benzol and alcohol; separating said heavy and lighter liquids one from the other and sub- .iecting the heavy liquid to a distilling operation in a vacuum corresponding to a temperature between 40 and 47 C. (l04-117 F.) to prevent denaturing of the zein to remove the benzol therefrom in the distillate.

2. Process of treating an aqueous alcohol solution of zein which comprises: mixing benzol with the solution in quantity sumcient to bring about a separation of the mixture into a heavy liquid containing zein, alcohol, water and some benzol, and a light liquid containing oil, coloring matter, benzol and alcohol; separating said heavy and lighter liquids one from the other; diluting the heavy liquid with alcohol; and then subjecting the diluted liquid to a. distilling operation in a vacuum corresponding to a temperature between 40 and 47 C. (104-l17 F.) to prevent denaturing of the zein to remove the benzol therefrom in the distillate.

v3. Process of treating an aqueous alcohol solution of zein which comprises: mixing benzol with the solution in quantity sumcient to bring about a separation of the mixture into a heavy liquid containing zein, alcohol, water and some benzol, and a lighter liquid containing oring matter, benzol and alcohol; separating said heavy and lighter liquids one from the other;

.and subjecting the heavy liquid to a distilling oil, 001- operation in which alcohol vapors are introduced into the liquid treated to displace the benzol therein.

4. Process of treating an aqueous alcohol solution of zeinwhich comprises: mixing benzol with the solution in quantities sufllcient to bring about a separation of the mixture into a heavy liquid containing zein, alcohol, water and some benzol, and a light liquid containing oil, coloring matter, benzol and alcohol; separating said heavy and lighter liquids one from the other; diluting the heavy liquid with alcohol; and subjecting the diluted liquid to a distilling operation in which alcohol vapors are introduced into the liquid treated to displace the benzol therein.

5. Process of treating an aqueous alcohol solution of zein which comprises: mixing benzol with the sohition in quantity sufllcient to bring about a separation of the mixture by gravity ,into a heavy liquid containing zein,' alcohol, benzol and water, and a light liquid containing oil, coloring matter, alcohol and benzol; separating said heavy and lighter liquids one from the other; and subjecting the heavy liquid to a distilling operation in which alcohol vapors are introduced into the liquid treated; benzol being added to the solution in such quantity as to bring about a reduction of the water content of the purified solution.

6. Process of treating an aqueous alcohol solution of zein which comprises: mixing benzol with the solution in quantity sufiicient to bring about a separation of the mixture by gravity.

into a heavy liquid containing zein, alcohol, benzol and water, and a light liquid containing oil, coloring matter, alcohol and benzol; separating said heavy and lighter liquids one from the other; subjecting the heavy liquid to a distilling-operation in which alcohol vapors are introduced into the liquid treated; and introducing benzol into the solution during the distilling operation in such quantity as to bring about a reduction of the water content of the purified solution.

7. Process of preparing zein in the form of a solution free from maize-oil, coloring matter, and

the solvent thereofv which comprises: extracting zein from maize gluten with an aqueous alcohol solution of 88%-95% concentration at a temperature of 55-65 C. (131-149 F.); mixing with the solution a suflicient quantity of benzol to bring about separation of the mixture into a light liquid and a heavy liquid; separating said light and heavy liquids one from the other;

. diluting the heavy liquid with alcohol; and subjecting the diluted liquid to a distilling operation in which alcohol vapors are introduced into the liquid treated to displace the benzol.

8. Process of preparing zein in the form of a i solution free from maize-oil, coloring matter, and

the solvent thereof which comprises: extracting zein from maize gluten with an aqueous alcohol solution of 88%-95% concentration at a temperature of 55-65 C. (13l-149 F.) mixing with the solution a suflicient quantity of benzol to bring about separation of the mixture into a from an alcoholic solution by distillation in quantity to bring about a separation of the mixture into a heavy liquid containing zein, alcohol, water and some of the maize oil solvent, and a lighter liquid containing oil, coloring matter, maize oil solvent, and alcohol; separating said heavier and lighter liquids, one from the other; and subjecting the heavy liquidto adistilling operation in a vacuum corresponding to a temperature of about 4047 C. (MW-117 F), to prevent denaturing of the zein, to remove the maize oil solvent therefrom in the distillate.

LLOYD CLAYTON SWAILEN. 

